This invention relates to a relatively large synthetic resin bottle-shaped container.
Biaxially oriented blow-molded bottle-shaped containers made of acrylonitrile resin or polyethylene terephthalate resin are popularly used because of their mechanical strength, transparency and other excellent properties.
Such biaxially oriented blow-molded bottle-shaped containers are generally divided into tow groups: those having a semispherically bulged bottom for an enhanced internal pressure resistivity and provided with a base cup that serves as a stand and those having a bottom with an internally depressed central area that serves as a stand for self-standing without a base cup.
A bottle-shaped body having a self-standing capability is advantageous over a bottle-shaped body provided with a base cup in terms of easy cleaning, sterilization, molding and assembling as well as of overall appearance.
However, a self-standing bottle-shaped body has only a small bottom area that supports the bottle-shaped body relative to the cross sectional area of a body portion and therefore is less stable when ti stands by itself.
More specifically, when a circular peripheral portion of the bottom that serves as a stand for the bottle-shaped body is formed by depressing the central area of the bottom by blow-molding, the circular peripheral portion of the bottom is inevitably located nearer to the center of the bottom than the outer circumference of the body portion. This fact results in the reduced bottom area that supports the bottle-shaped body in an upright condition.
Moreover, when a high internal pressure is applied to such a self standing bottle-shaped body, the bottom portion forming a stand is subjected to a relatively large expansion, which in turn adversely affects the self-standing capability of the bottle-shaped body to a significant extent. Such an expansion can results in an deformation.
On the other hand, in a bottle-shaped body provided with a base cup for keeping it upright, the height of the base cup is required to be of a relatively large size in order to accommodate an outwardly projecting semispherical bottom portion of the bottle-shaped body so that the overall appearance of the bottle-shaped container will be aesthetically poor because of the disproportional large base cup. Moreover, the bottom of such a bottle-shaped body can not protect expansion and deformation when a large internal pressure is applied thereto.
Besides, a biaxially oriented blow-molded bottle-shaped container made of acrylonitrile resin is insufficiently resistive to shocks applied to the bottom and can produce cracks and fissures on the bottom when it is inadvertently dropped.